siemens s 400
Hello, rmmaran
Regarding the time it will take, I think that depends more on your own background than on any other thing.
I'll would suggest you study the electrical drawings and project specs before going deeper in the PLC an SCADA programs.
Next, try to talk with anybody who works or operate the instalation to know what are the most common failures and try to concentrate on this: what are the software routines related to that kind of failure, the variables involved, the operational logic and how you possibly diagnose that failure the next time it aroses.
Hope this helps, good luck and best regards!